Temperature-Compensated Multi-Point Strain Sensing Based on Cascaded FBG and Optical FMCW Interferometry

Area of Science:

• Optoelectronics
• Fiber Optic Sensing
• Strain Measurement

Background:

• Accurate multi-point strain and temperature sensing are critical in various engineering applications.
• Existing methods often face limitations in multiplexing capabilities and simultaneous measurement of strain and temperature.

Purpose of the Study:

• To develop and demonstrate a novel temperature-compensated multi-point strain sensing system.
• To integrate Fiber Bragg Gratings (FBGs) for simultaneous strain and temperature sensing with optical Frequency Modulated Continuous Wave (FMCW) interferometry for position information and multiplexing.

Main Methods:

• Utilized cascaded FBGs for simultaneous strain and temperature sensing.
• Employed optical FMCW interferometry for position reading and multiplexing.
• Used a narrow linewidth laser with continuous frequency-sweeping as the light source.
• Demodulated beat-frequency signals to obtain link information and measured strain/temperature values using a sensing matrix.

Main Results:

• Achieved precise position information reading with an accuracy of 50.15 mm over a 16 m fiber.
• Demonstrated a wide dynamic range of up to 22.68 dB.
• Successfully measured strain from 0 με to 7000 με and temperature from 20 °C to 90 °C.
• Obtained high sensitivity to strain (1.163 pm/με) and temperature (10.21 pm/°C), with strain accuracy of 10 με.

Conclusions:

• The proposed system effectively performs temperature-compensated multi-point strain and temperature sensing.
• The integration of FBGs and FMCW interferometry offers significant advantages for quasi-distributed sensing.
• The system holds substantial practical importance for applications requiring precise strain monitoring.